1. Field of the Invention
The present invention relates to high depth, low force throw away cutting inserts to turn ductile material like steel at low to high cutting speeds and medium to high ranges of feed and depth of cut.
The present invention further relates to a high depth, low force throw away cutting insert which is capable of withstanding mechanical impact under interrupted machining conditions without effecting the cutting life of the tool.
The present invention further relates to a high depth, low force throw away cutting insert to turn ductile material which maintains good chip control.
2. Description of the Related Art
Chip control inserts are well known in the art where a island on the face of the insert adjacent the cutting edge terminates in a ramp shoulder in the flow path of the chip serving to curl and/or break the chip. It is also known in the art to provide a positive rake cutting action serving to decrease power requirements either by tapering the sides extending to the cutting edge or providing a positive rake land on the face perimeter extending from the cutting edge. Special chip breaking effects have been achieved by providing a series of chip deflecting grooves or depressions spaced along the cutting edge such as is disclosed in U.S. Pat. Nos. 4,215,957; 4,273,480 and 4,335,984.
Recess grooves or faces with chip breaking projections are also known in the art, particularly for use in turning operations such as are disclosed in U.S. Pat. No. 3,792,514 wherein a uniform concave groove in provided along each cutting edge of the insert for chip breaking in heavy cutting in combination with a nose projection in the concave groove isolated from an island on the insert serving for chip breaking in light cutting operations. Another form of such insert is disclosed in U.S. Pat. No. 4,214,845 including a pair of chip breaking projections at each corner with another projection on the bisector behind the first projections. Another insert is disclosed in U.S. Pat. No. 4,626,141 wherein good chip control is achieved, but there is still some improvement to be made in the areas of chip deceleration and wear of the insert during cutting.
McCreery, U.S. Pat. No. 4,318,645 discloses a polygonal insert of a hard, wear resistant material. The insert includes a bump behind each corner of the insert which serves as a chip breaker. The bump is separated from the cutting edge land by a lower secondary land which has its maximum height and width in each corner area of the insert. The height and width gradually decrease as the secondary land extends away from the corner area in a direction parallel to the cutting edge.
Malaker et al., U.S. Pat. No. 4,626,141 discloses a polygonal shaped chip control insert characterized by a chip control groove extending across the insert corners and along an edge extending from these corners with increasing width away from the cutting corner. The groove is formed with a radius extending below a narrow positive rake cutting edge land to a maximum depth tangent with the bottom of the groove.
The present invention differs from all these developments of the prior art because it offers improved mechanical impact strength which is useful when there are interrupted machining conditions, and allows the insert to turn ductile material such as steel at low to high cutting speeds and medium to high ranges of feed and depth of cut.
It has long been a problem in the art to arrive at a disposable cutting insert which is capable of turning ductile materials and yet be affordable, and offer different feed rates and depths of cut. The present invention meets these long felt needs and offers a chip breaking capability range which is surprising, especially in view of the different feed rates at which the insert is designed to operate.
It is therefore an object of the present invention to provide for a disposable insert to turn ductile material at low to high cutting speeds and medium to high ranges of feed and depth of cut.
It is a further object of the present invention to provide a disposable cutting insert which exhibits excellent chip breaking capability over a wide range of feed rates and depths of cut, an lower consumption of cutting forces and horsepower.
It is a further object of the present invention to provide a cutting insert which exhibits improved wear resistance.
It is a further object of the present invention to provide for a cutting insert which has excellent impact strength.
It is a further object of the present invention to provide a insert with a double step island to minimize insert chipping and provide superior chip breaking capabilities.
Other objects and uses for the cutting inserts of the present invention will become apparent to those of ordinary skill in the art after a reading of the specification and claims.